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Maunsell Army Forts in WWII


A Copy Free feature of research into the Thames Estuary Army Forts in WWII by Evert Jan-Foeth of 'On The Slipway'

Click for large images

Issue: 1 Date: 21st February 2021

WO_199_2576_001

Image 1. WO_199_2576_001

Showing the various layouts contemplated

WO_199_436_048

Image 2. WO_199_436_048

Location of the three sets of Thames Estuary Army Forts at Nore, Red and Shivering sands with areas of prohibited shore side shelling

Army Fort Plans Army Fort Plans Army Fort Plans

Image 3. 4 & 5. Army Fort Plans

The actual layout: Oxford Picture Frame Base and Cross Section

Army Fort Plans

Image 6. Army Fort Plans

Leg Top and Capping

Army Fort Plans

Image 7. Army Fort Plans

Catwalk detail

Army Fort Plans

Image 8. Army Fort Plans

Catwalk Roller Bearings to take up weather elements and gun recoil

Army Fort Plans

Image 9. Army Fort Plans

Bofors and Control Tower Top and Intermediate Levels

Army Fort Plans

Image 10. Army Fort Plans

Bofors and Control Towers Bottom Level, Searchlight and 3.7" Gun Tower Top Levels

Army Fort Plans

Image 11. Army Fort Plans

Searchlight and 3.7" Gun Towers Intermediate and Bottom Levels

Army Fort Plans

Image 12. Army Fort Plans

Bofors Gun Tower (Mersey) Elevation

Army Fort Plans

Image 13. Army Fort Plans

Floating out arrangement

The Army Fort Documentation zip file

Cobtrol Tower

Image 14. Control Tower

Showing at right the outline of the Gun Layer Radar No3, Mk II, placed in a sponson dropping 4 feet down from the top of the tower. Three timber packs where this truck could place its supports are already indicated on the plans

On the left side a Sperry (?) Predictor was placed, as well as one height finder and one telescope, height finder may have been somewhat limited in rage

Sperry Predictor and Radar No 3

Image 15. Sperry Predictor and Radar No 3 with IFF antenna

The radar antenna is not visible and may been censored out (It could be folded down)

Searchlight Tower

Image 16. Searchlight Tower

On the front of the Searchlight Tower of Shivering Sands two small pieces of equipment are visible; these have been identified as an Maxson M33 mount. The M33 is a small self-powered twin 0.5" Browning machine gun turret typically fitted to the US M14 Halftrack intended to be supplied to the British under the Lend-Lease. The M33 mount was quickly replaced by the M45 with four machine guns. The outline in the guard rails is visible to this day, but there is no mention of these guns on the plans

In the rear a small antenna can be seen on the Bofors Tower, The smaller aerial is Light Warning Set, known as AMES type 6 (RAF ) or the Radar, AA, No4 Mk3 (Army) that was often mounted on the roof of a small truck

The Mersey Forts were equipped with an earlier version of this radar and I have been able to find only one image of that radar at MRATHS (Malvern Radar & Technology History Society)

Mararet Hide at Shivering Sands

Image 17. 'Margaret Hyde' at Shivering Sands

This general overview with the re supply trawler 'Margaret Hide' shows another surprise; a parabolic radar antenna plus installation on the Searchlight platform

A rear view image of the Fort from an IWM movie clip shows a sizeable installation

I've been in contact with Ian Brown, curator at the National Museum of Flight and a radar expert; there was no parabolic radar dish in use at that time other than the SCR-584

The size of the entire installation suggests, similar to the Radar No3, that the entire 10 ton truck was hoisted 'on board' after the Forts were placed

Note that in the rear-view shot of the Forts that the Searchlight was still present

The two small structures on the roof of the Searchlight Tower have been identified as a M33 Maxson mount, a US-built twin 0.50" gun mount

Maxson Mount M45 Quad Version

Image 18. Maxson Mount M45 Quad Version

It is still very difficult to find images but I'm not entirely sure above the m13/14/16 designation. The m13/14 were the twin-gun versions, the m16 the quad gun version that replaced them. Not an expert in this part of the vehicle taxonomy at all, but there are plenty pages up such as:

https://military.wikia.org/wiki/M14_Half-track

Don't know if the british received the M13 or M14 the link suggests the M14. I did find out that if you look for images you'll mainly find the quad M16 version

Follow the outline on the Army Forts you'll notice they are the same which is a surprise as they are not mentioned anywhere

A WII Antique Dealer has several of these mounts, they might make a nice garden ornament!

Radar Set SCR-684

Image 19. Radar Set No 3 MKII

Army Fort

Image 20. Army Fort

Radar Set SCR-684 Truck complete on the Control Tower

Note: The Mersey Forts used a different set

Army Fort Radar

Image 21. Army Fort Equipment

Radar equipment note the 'Light Warning Set', No 2 Mk III, AMES type 6 or No4 Mk III are different designations for the same set

Sarah and Margaret Hide

Image 22. 'Sarah' and 'Margaret Hide'

Lowestoft Steam Drifter

Image 23. A Lowestoft Steam Drifter makes port in heavy seas


Audio

Tendering the Forts with an audio impression of the four 3.7" Heavy Anti-Aircraft Guns Firing

Handbook for the Ordnance Q.F (Quick Firing) 3.7" MK II Gun (1940) Overview

Image 24. Handbook for the Ordnance Q.F (Quick Firing) 3.7" MK II Gun (1940) Overview

3.7" Gun Handbook Cover Detail

Image 25. 3.7" Gun Handbook Cover Detail

3.7" Gun Handbook Gun Barrel Detail

Image 26. 3.7" Gun Handbook Gun Barrel Detail

3.7" Gun Detail 3.7" Gun Detail

Image 27 & 28. 3.7" Gun Detail

3.7" Gun Detail

Image 29. 3.7" Gun Detail

3.7" Gun Detail

Image 30. 3.7" Gun Detail

3.7" Gun Detail

Image 31. 3.7" Gun Detail

3.7" Gun Detail

Image 32. 3.7" Gun Detail

3.7" Gun Detail

Image 33. 3.7" Gun Detail

3.7" Gun Detail

Image 34. 3.7" Gun Detail

3.7" Gun Detail 3.7" Gun Detail

Image 35 & 36. 3.7" Gun Detail

References: J.A. Posford, 1948, 'The Construction of Britain's Sea Forts', The Civil Engineer, Volume 3

Handbook for the Ordnance Q.F. 3.7" Mark II Gun 1940

With grateful thanks to Evert Jan-Foeth of 'On The Slipway' for the material, editing and sharing his comprehensive research

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